If you are in your 30s, green leafy vegetables are a must in your diet.

Spinach, avocado and kale are rich in lutein, a nutrient that our body cannot make on its own(Shutterstock)

Here’s another reason to consume lutein-rich foods, as a recent study has suggested that eating spinach, kale and avacados in middle age will not only keep you physically, but cognitively fit as well. Lutein is a nutrient that the body cannot make on its own, so it must be acquired through diet. Lutein accumulates in brain tissues, but also accumulates in the eye, which allows researchers to measure levels without relying on invasive techniques.

Researchers from the University of Illinois at Urbana-Champaign analysed 60 adults aged 25 to 45, found that middle-aged participants with higher levels of lutein - a nutrient found in green leafy vegetables such as spinach and kale, as well as avocados and eggs -- had neural responses that were more on par with younger individuals than with their peers.

Resarcher Naiman Khan said that now there’s an additional reason to eat nutrient-rich foods such as green leafy vegetables, eggs and avocados as other than health benefits, the data indicates that they may have cognitive benefits as well.

“As people get older, they experience typical decline. However, the research has shown that this process can start earlier than expected. You can even start to see some differences in the 30s,” said first author of the study Anne Walk. “We want to understand how diet impacts cognition throughout the lifespan. If lutein can protect against decline, we should encourage people to consume lutein-rich foods at a point in their lives when it has maximum benefit,” Walk added.

They measured lutein in the study participants’ eyes by having participants look into a scope and respond to a flickering light. Then, using electrodes on the scalp, the researchers measured neural activity in the brain while the participants performed a task that tested attention.

“The neuro-electrical signature of older participants with higher levels of lutein looked much more like their younger counterparts than their peers with less lutein,” Walk said. “In this study we focused on attention, but we also would like to understand the effects of lutein on learning and memory. There’s a lot we are very curious about,” Khan noted. The finding appears in the journal Frontiers in Aging Neuroscience.